Wind of Duplicity is a powerful spell, a relic of the Lost Ages. It has the ability to affect an entire world, either masking the people from detection, or hiding the doings of a world's inhabitants. In the Demon Spawn War (8972 GE - 9493 GE), the latter effect was used by Asmodeus and his loyalists generals. On Dis, they cast the Wind of Duplicity, hiding for a time, the making of their devil legions.
Detailed more in the Duplicity Period, the other effect was used by Neld-Rac on the world of Bal-Kriav. He made it so it was impossible to use divination magic and other spells to detect one's nature.
Requiring psyche pooling of eight or more high-powered individuals, this spell is extremely hard to cast.